Accumulation of moisture in the tracks of sliding windows and the removal thereof has long been a source of intense investigation, particularly with regard to sliding windows installed on buildings. In order to maintain the desired profile of the window with respect to the facade of the building, it is desirable to have the window either flush with the rest of the exterior of the building or offset towards the interior of the building. Accordingly, most sliding window drainage systems remove water from the track closest to the interior of the building by first having the water drain vertically from the track and then travel substantially horizontally where the drainage system converges with the water flowing from the track closest to the exterior of the building. The water combined from both tracks typically empties from the sill through a common exit port. Unless one-way valves or other means for preventing reverse flow into the drainage system are placed within the system, these windows will be prone to leakage and/or blockage.
Numerous unique systems have been proposed which seek to limit the possibility of water being pushed back through the drainage system into the interior of the building. For example, Dallaire (U.S. Pat. No. 5,887,387) describes a drainage system having a flap covering the drainage aperture that is urged open when water flows from the tracks outwardly to the environment. However, the flap cannot be pushed in the other direction allowing air or water to enter the tracks from the outside environment. In addition, vents are provided within the system to assist in expelling the water from the tracks.
Gould (Canadian Patent Application No. 2,319,400) describes a one-way valve that is positioned on the window frame near the interior of the building. The valve permits the outflow of air and water from the interior of the building when the pressure in the building is higher than the outside pressure and prevents the flow of air into the building when the pressure outside is higher than the pressure in the interior of the building.
Jolly (U.S. Pat. No. 3,845,599) describes a window drain valve that uses a cylindrical rod that rises and falls in accordance with the level of water in the window frame. When the maximum amount of water has accumulated in the interior of the window frame the cylindrical rod is urged against an aperture in the track of the window, thus preventing water from entering back into the track.
Drainage systems for patio doors and fixed windows positioned in a door have also been proposed. For example, Hope (U.S. Pat. No. 5,890,331) describes a drainage tube that is inserted into the support frame for a window positioned in a door. The tube is used to connect the window receiving pocket within the support frame to the exterior environment. The system described by Hope is particularly directed to fixed windows accommodated in doors having a single window receiving pocket and does not address the problem associated with draining two or more window receiving pockets or tracks. Therefore, the system described by Hope could not be readily adapted for use with sliding windows having two or more tracks.
The application of sliding windows on structures that are capable of movement, such as boats and other vehicles, presents additional challenges in terms of trying to remove moisture that accumulates in the tracks of the window. The movement of the vehicle causes air to be channelled down the tracks urging water to rapidly accumulate in the corners of the window. Therefore, a need exists to provide a drainage system for sliding windows on vehicles that is capable of rapidly removing water from the tracks. In addition, a moving vehicle is subject to exposure to airborne debris, which could enter a drainage system and/or passage and block the outflow of water from the window frame. According it is desirable to have a window drainage system that has separate drainage passages for each track that the glazing material moves along, which are devoid of a horizontal sections and whereby the drain passages are as short as possible to ensure that any debris that enters the passage will quickly be dispersed by the outside air moving across the exterior opening of the passage.